Blind-end hole forming device for poured concrete slabs



Dec. 27, 1955 L. A. WHITLOCK 2,723,126

BLIND-END HOLE FORMING DEVICE FOR POURED CONCRETE SLABS Filed April 6. 1955 Fi i- 8 7 2 ii, 10 1 I ,1 ,1 I

INVENTOR Leslz'efl. ZD/rz'floclc BY M2;

ATTORNEYS The present invention is directed to, and it is a major object to provide, a novel device for forminga bl nd-end hole in a poured concrete zslah, yet with rthe blind end adapted to be driven out to produce .a .hole through the slab open at both "ends.

The device is two-part and is initially supported from .a form on or against which the concrete slab is subsequently poured. U'p'on'stripp'ing of the fform, one Jpa'rtiof the device removes therewith, leaving the other ,part within the blind-end hole; such other "part being'a'd'a'pted to be driven out of the hole in a direction to open its blind end when desired, and for the purpose of permitting the installation of utility conduits through said hole in the slab, or the mounting in the hole of utility outlets on one side of the slab with access from the other side.

Another important object of the present invention is to provide a blind-end hole forming device for poured concrete slabs, wherein such device is readily manually adjustable in effective length so that the device may be accommodated to concrete slabs of varying thickness.

An additional object of the invention is to provide a device, as in the preceding paragraph, which includes telescopic sleeves, and wherein said adjustment is accomplished by a novel arrangement of nubs on one sleeve cooperating with ratchet-edges in the other sleeve disposed diagonal to the transverse or radial plane of said telescopic sleeves.

It is also an object of the invention to provide a blindend hole forming device for poured concrete slabs which is designed for ease and economy of manufacture, and convenience of use.

Still another object of the invention is to provide a practical, reliable, and durable blind-end hole forming device for poured concrete slabs, and one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

Fig. 1 is a perspective view of the device, detached.

Fig. 2 is a sectional elevation of the device looking in the same direction as Fig. 1, but showing the device as in use, though prior to strippingof the form.

Fig. 3 is a sectional elevation of the device, detached, taken on line 3-3 of Fig. 1.

Fig. 4 is a similar view to Fig. 2 but after stripping of the form and removal therewith of the fixed sleeve.

Referring now more particularly to the characters of reference on the drawings, the device comprises a fixed sleeve 1 and an adjustable sleeve 2; the latter sleeve being telescoped into the fixed sleeve 1 in relatively close fitting but manually adjustable relation.

The fixed sleeve 1 is secured at its outer end by an annular flange 3 to, and opens through, an enlarged attachment plate 4 of rectangular configuration.

United State patfim 2 The sleeve 1 projects 'at a right angle from the attachment plate 4 and 'is preferably fastened to the annular flange by spot-welding or the like.

At'the corners thereof the attachment plate 4 is formed with holes 5. The adjustable :sleeve '2 has :a bafiie plate 'or disc 26 disposed :therein radjacent :but short :of the outer end 7; the disc 6 being held in place by an outturned annular flange .:8 attached to the sleeve 2 onithe inside, as zb'ygspot-welding or the like.

The adjustable sleeve2 is cut,'on'opposite sides and :at its inner end, with a pair .of notches 9 of circumferentially elongated, right angle-triangulariform.

The notches 9 thus define opposed circumferential edges 10 which "are generally a part of a -helix landtextend diagonal to the transverse or radial plane :of the telescopic sleeves. Such edges 10 are saw-toothed or ratchetcut, asshown.

0n opposite sides thereof the afixed :sleeve :l is provided with .inwardly deformed vnubs or detents '11 .alined with .each other and adapted for cooperative engagement with the ratchet edges lit-of the notches'9.

When the device .is in use the attachment plate 4 :is

abuttedat a;pre-selected point againsttthe inner :face :of 2a form 1 2 on-or against which a concreteslab 13 =is subsequently .poured; the .attachment plate 4 being secured to the "form 12 by nails 14 driven through the holes 5.

With the attachment plate 4 so mounted on the form 12, the assembly of telescoped sleeves 1 and 2 projects from the form in a direction for embedding in the concrete slab 13 when it is poured.

In advance of pouring of said concrete slab 13, the effective length of the assembly of the telescoped sleeves 1 and 2 is adjusted so that such length is only slightly less than the known thickness of the slab 13. This adjustment is accomplished by manually rotating the sleeve 2 in the fixed sleeve 1 whereby to cause the ratchet edges 10 to move in one direction or the other relative to the inward detents 11.

As the ratchet edges 10 are diagonal, rotation of the sleeve 2 in one direction causes it, by the cooperative engagement of said edges and the detents 11, to move outwardly, whereas rotation of said sleeve 2 in the opposite direction permits the same to be adjusted inwardly.

When the sleeve 2 is adjusted to proper position it maintains the latter by reason of the engagement of the detents 11 with the ratchet edges 10 at the point of setting; i. e., there cannot thereafter be any accidental telescopic reduction in the effective length of the device during pouring of the slab.

After adjustment of the device, as above, the slab 13 is poured; the surface of the slab opposite the form 12 lying only slightly beyond the outer end 7 of the adjustable sleeve 2, and the latter being filled with a knock-out plug 15 of concrete.

After the concrete slab 13 has set the form 12 is stripped away, carrying with it the attachment plate 4 and the fixed sleeve 1; the initially adjustable sleeve 2, together with the bafile 6, remainingfor the momentwithin the slab 13.

This produces a blind-end hole 16 in the concrete slab When it is desired to open the blind end of the hole 16 a suitable punch (not shown) is engaged in such hole from its open end, projecting into the sleeve 2 and abutting the bafiie disc 6 from the back side. The punch is then struck forcefully with a hammer, which drives the sleeve 2 and battle disc 6 in a direction to fracture the plug 15 and knock it out of the concrete slab 13; the point of fracture offering little resistance, as it lies solely between the outer end 7 of the sleeve 2 and the closely adjacent face of said slab 13.

Upon knocking out of the plug 15 in the manner above described, the hole extends through the Wall and is open 3 at both ends for the installation of a utility conduit or the mounting of a utility outlet.

Also, as the outer end of the adjustable sleeve 2 lies short of the adjacent surface of the slab, such surface can be accurately finished smooth and level Without interference from the device.

From the foregoing description it will be readily seen that there has been produced such a device as substantially fulfills the objects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

1. A device for producing a blind-end hole in a poured concrete slab initially backed by a form, said device comprising a pair of engaged and turnably telescoped generally smooth-faced sleeves, means to secure the outer end of one sleeve on the inner face of the form, the other sleeve being closed adjacent its outer end, the inner end of the inner one of said sleeves having an elongated circumferentially extending notch diagonal to the radial plane of the sleeves, the edge of the notch being of ratchet form, and a nut on and projecting radially inwardly from the other one of said sleeves intermediate its ends and engaging said ratchet edge to retain the sleeves against contracting movement.

2. A device for producing a blind-end hole in a poured concrete slab initially backed by a form, said device comprising an outer generally smooth-faced sleeve, means to secure said sleeve at one end on the inner face of the form, an inner smooth-faced sleeve turnably and slidably projecting into and engaging the outer sleeve from its other end and projecting outwardly from said end, the inner sleeve being closed adjacent its outer end, the inner end of the inner sleeve having an elongated circumferentially extending notch, one edge of which is diagonal to the radial plane of the sleeve, said edge of the notch being of ratchet form, and a nut projecting inwardly from the outer sleeve intermediate its ends and engaging said ratchet edge in sleeve-position retaining relation.

References Cited in the file of this patent 

